Sound-amplifier.



B. FRITZSCH.

SOUND AMPLIFIER.

'APPLICATION HLED )UNE 5, :916.

Patented Apr. 17, 1917.

gum/nuff BERNHARD FRITZSCH, 0F CINCINNATI, O HIO.

SOUND-AMPLIFIER.

Specification of Letters Patent.

Patented Aplnl'?, 1917.

Application led .Tune 5, 1916. Serial No. 101,669.

To all whom z't may concern.'

Be it known that I, BERNHARD FRrrzscH, a citizen of the United States, and resid! ing at Cincinnati, in the county of Hamilton and State of Ohio, have invented a new and useful Improvement in Sound-Amplifiers, of which the following specification is a full disclosure.

My invention relates to an improved tone chamber or sound amplifying compartment for a phonograph,vhaving superior properties in relation to either the recording or reproducing of sound.

The object of the invention is to so construct the chamber communicating with the sound tube, that it will not only amplify the volume of sound materially, but will also serve as a factor or an influence in the correct recording or reproducing of musical tones with their true and full values.

To this end, I have devised a` tone chamber embodying the principles of a musical instrument structure, isuch as the violin, Zither or guitar type, or combining the more desirable characteristics of several different musical instruments, with a unitary tone value result.

In general, attempts to amplify the sound waves have been at the expense of tone effect, while I have succeeded in increasing the volume while preserving the characteristic over-tones of the voice or instrument.

The features of the invention will be more fully set forth in the description of the accompanying drawings, forming a part of this specification, in which Figure l is a central vertical section through the instrument.

Fig. 2 is a front elevation.

Fig. 3 is a section through the tone chamber on line 3-3, Fig. 1.

Fig. 4 is a detailed section of one corner of a modified form of tone chamber.

In the drawings, I havenot shown the motor but a box or cabinet in which the operative parts are disposed as usual. The cabinet has a large main compartment 1, forming an indirect tone chamber in which the direct tone chamber is located. As shown, the chamber 1 is defined by a top 2, bottom 3, back f1, sides 5 and 6, being open at the front end 7. A tray-lid 8 is hinged to the back forming a compartment 9, in which is the turn-table 10, on the piece 2, a sound-boX or reproducer l1, and a horizontally pivotally swinging sound-arm 12, ta-

pering appropriately and having a vertical rearV end 13 passing downward through the piece 2 into compartment 1, where it communicates with a sound tube or throat 14, having a boss 11, secured to the back 4.

The direct or tone chamber proper 15, has a reduced open rear end 16 communieating with the sound tube 14, and an enlarged open front end 17 at the open end of the main compartment.

Preferably the tone chamber is in the general shape of the frustum of a pyramid, having forwardly diverging walls, although the matter as to whether the cross section is clrcular or polygonal is not of the essence of the invention.

The tone chamber is double walled, formed of thin sounding board material, such as wood of the quality and dimensions employed in violin or Zither structures. As preferred and shown, the chamber walls are formed by fiat sounding boards, four sided, and jointed at theirmeeting edges respectively. So, the inner wall member 18 of the tone chamber is formed of four flat sounding boards, and the outer wall member 19 is also formed of four flat sounding boards, the outer and inner walls being uniformly spaced apart to provide the sound pocket 20, closed at the rear ends by members 21, and at the front ends by members 22.

The mouth 23 of the throat has a crosssection to correspond with the reduced end of the tone chamber and the throat and reduced end of the chamber are secured together to form a continuous and uniformly diverging sound conduit. Preferably the inner wall is transversely reinforced by rigid bars 24, and preferably the outer or inner walls, or both, are formed with sound holes or apertures 25, these being shown for illustration, only in the outer walls, and preferably, also, the front members 22 are formed with sound apertures 26 at the front of the cabinet.

If desired, the double walls may be provided with the diagonal partitions 27 (see Fig. 4) so that the tone chamber is constituted by a plurality of instrument bodies, each resembling a violin in structure and tone quality.

While increasing the sound volume, the fullness and roundness of the tone is preserved. The Walls reverberate under the sound-wave influence exactly as they do when -an instrument is played, so that the overtones are individualized and fully recorded or reproduced. y

rlhe sound waves set into vibration by the reproducer are transmitted through Ithe tubular sound arm 12 and through thesound conductor 14 to the amplifying resonator surrounded by resonating chamber or chambers. The sound conductor 14 is rigid so that sound waves will be conveyed from the sound boX to the resonant body of the amplier without loss of energy.

The resonant sound boards or sides of the amplifier are vibrated and the relative opposite Walls are set into sympathetic vibration with and by the sound waves passing through the centralamplifier passage leading from the sound boX and by the vibration of these sound walls, the sounds corresponding to the vibration are reproduced and augmented. These inner amplifier walls being of thin resonant material are each strengthened by spaced cross-bars, adding resonance to produce solid tones and avoid undue vibration, and thus all' harsh or sudden noises due to irregular or discontinuous vibration are modified to musical sounds or tones. By making the amplifier of rectangular form, tapering from the inlet end outwardly toward the outlet end, with each wall of a resonant material, its range is materially increased and quality of sound improved with all metallic or hard sound or noises eliminated. y

rllhe amplifier is surrounded by a resonating chamber or chambers, constituted by the spaced double walls, to form an intermediate unconned chamber closed at the inlet end of the amplifier by a rigid end wall, as not to be in communication with the rigid sound conductor, so that no direct sound waves from the reproducer can be admitted.

'ln the arrangement shown with the amplifier of square form in cross section, each side has two parallel walls of resonant material spaced apart with the outside wall apertured, and the intermediate chamber' open at its front end, through apertures in the front end wall. The companion walls form horn. or trumpet amplifiers for conjveying sound waves, resulting from the vibration of the walls and they are set into sym-- pathetic vibration to augment and emit tones which otherwise would be lost. `With one of thepair of resonant walls apertured to conform to a musical instrument, provided with a sound hole, gives greater elasticity and increases the volume of tone. Sound waves set up by instrument are discharged from the instrument directly from the sound-box through the central passage, others through the resonant chamber at chambers surrounding such central passage and thus rendered audible are not lost within the cabinet of the machine. Harsh noises are either eliminated or modiiied to musical tones, so that in the whole, sounds are lemittedvmore agreeable to the ear and with a more accurate and mellow reproduction of' sound.

It is obvious that the contour or shape or proportions of the double wall tone chamber can be variously modified in view of this disclosure without departing from the principles of the invention.

l have found that the musical values of the voice or instruments, alone or combined, are materially amplified and improved when transmitted through a tone chamber embodying the principles and characteristics herein disclosed.

Having described my invention, l claim:

1. In a talking machine, in combination, a sound conduit, a double walled resonant sound ampliiier formed with a central passage-way communicating at one end with said conduit, said double walled construction forming a resonant chamber as an unconfined air space surrounding the passageway and non-communicative with said conduit.

2. ln a talking machine, a sound conduit, and a hollow sound amplifying body comprising a resonant walled structure forming a sound passage communicating with said conduit, with a resonant chamber as an unconfined air space around said passage noncommunicating with said conduit.

3. in a talking machine, a sound amplifier of hollow walled structure formed with a central sound passage-way and resonating amplifying chamber as an unconned air space about said central passage-way noncommunicative with said passage-way `for emitting sound waves `set od by the vibration of the walls.

4. ln a talking machine, a tapering sound conduit, a sound amplifying body having its sides each of double parallel walls spaced apart, forming a central amplifying sound passage communicating with said sound conduit, and the space between the walls, a resonator chamber open at its forward end and non-communicating with said sound conduit for amplifying sound waves set up by the vibration of said walls, or one of them.

5. ln a talking machine, a sound conduit, a sound amplifying body having itssides each of double walls spaced apart and of resonant material, the outer wall provided with a sound hole, said double walled sides forming a central sound amplifying passage communicating with said conduit and continuous therewith, and each side a resonating amplifying chamber non-communicating with said conduit.

G. ln a talking machine, a sound conduit, a sound amplifying body having its sides each of double walls ot resonant material. spaced apart and connected at the rear end lil@ to Close the chamber formed by said Walls and open at the oppositel end, said double Walled sides forming a central sound passage connected with said conduit, and each side a resonating chamber non-communicative with said conduit.

In Witness whereof, I hereunto subscribe my name, as attested by the two subscribing Witnesses.

BERNHARD FRITZSCH. Vtnesses:

EMMA SPENER, L. A. BECK. 

